This is a DIY in building an exhaust box to use a window shaker a.c. unit indoors. Tools needed -box material. I used R max R matte +3 good for up to 250*f and is 3.2r value - sharp knife tape measure 3m hvac tape (don't use duct tape) Little common sense 6" flex duct joiner/sleeve piece 6" 90* elbow Hose for drip tube after you mount your a.c. and like it's final position, it's time to build your exhaust box. I made my box with 2 layers of material for added protection. Build 1 section at a time. Fully secure at each spot. I personally do 3 layers of tape (overlapping each other like a brick wall for support). See pics below for details. I use a 6" duct joiner/sleeve Mounted on top where I attached my insulated flex duct to for the exhaust part. I did 2 layers of the board material. This gives me a 6.4 R value. Noise is barely heard as well. There is no heat on the boards, donuts insulated well. I will also build a shelf support under the bottom of the exhaust box just for added support. Only thing that's holding it is 3m hvac tape. But it's secured very well. Pictures will.help more than my description, I'm sure.